Abstract
Several basic problems in quantitative immunoelectron microscopy were investigated. The catalase activities in the liver homogenate of guinea pig, rat, Chinese hamster and mouse were assayed biochemically, while the peroxisomal labeling density (gold particles/μm2) for this enzyme of the same animals was determined by protein A-gold technique. The species difference of the enzyme activity did not correspond to the difference of the labeling density. Furthermore, the difference of the enzyme activity did not correspond to the staining intensity of the signal developed by immunoblot for catalase. However, the labeling density largely corresponded to the immunoblot data. Peroxisomal labeling densities of the above animals were determined by protein A-gold technique using rabbit anti-rat liver catalase (RLC) or guinea pig anti-RLC. The data obtained by the rabbit antibody was not consistent with those obtained by the guinea pig antibody. Moreover, we investigated the relationship between antigen concentration and labeling density using a model system in which bovine serum albumin (BSA) or purified RLC is directly mixed with LR White resin at various concentrations. The labeling density was directly proportional to the antigen concentration within the examined range. The results clearly demonstrate that the antigen concentration is expressed by the labeling density. Such proportionality is realized only between the same species. Taken altogether, we could compare data obtained quantitative immunoelectron microscopy between the same species even if using the same lot of antibody.
